Glasgow A's tries came from skipper Ben Afshar, Jonny Morris and a double by Logan Trotter.
Richie Simpson and Matthew Urwin added the other points from the tee.
Luca Bardelli, Jamie Shedden and Robert Beattie scored for the Bulls.
Glasgow A
14 Ben Salmon
13 Duncan Munn
12 Kerr Yule
11 Logan Trotter
10 Richie Simpson
9 Ben Afshar
1 Callum Smyth
2 Angus Fraser
3 Callum Norrie
4 Ryan Burke
5 Sintu Manjezi
6 Ruaraidh Hart
7 Jonny Morris
8 Jack Mann
Substitutes
16 Grant Stewart
17 Allan Dell
18 Murphy Walker
19 David Andrew (Marr Rugby)
20 Mark McCormick (Newton Stewart)
21 Sean Kennedy
22 Matthew Urwin
23 Amena Caqusau